This invention relates to an apparatus and method for continuously producing a twisted baked good such as twisted breadsticks.
In the production of twisted food products such as licorice, a licorice mass is heated to high temperatures to reduce viscosity of the licorice and to permit continuous extrusion of a twisted licorice rope through rotating nozzles. The production of twisted gum ropes is disclosed in U.S. Pat. Nos. 5,626,892 and 5,955,116 to Kehoe et al. Prior to twisting, heaters may be employed to control gum softness for extrusion, and for curing and sealing of the gum in a liquid additive injection zone of the gum extruder.
A braiding extruder for making braided products from extrusible material such as a dough or batter is disclosed in U.S. Pat. No. 5,834,040 to Israel et al. U.S. Pat. No. 5,695,805 to Borek et al discloses the production of ready-to-eat cereals and cereal-based snacks from multiple extrudate strands of cooked cereal dough that have been twisted or braided into ropes immediately after extrusion and severed into pieces.
U.S. Pat. No. 5,670,185 to Heck et al discloses an extrusion die assembly for preparing articles which are twisted and/or filled in their center with a filling, having one or more strands which are of a pasta-type or expanded cocktail snack-type. The extrusion die assembly comprises a thick body member which rotatably houses a barrel member which provides a tubular passage. The body member has an outlet channel for passage of a plasticized, especially edible, substance to the barrel member tubular passage which extends from a junction with the body member to at least one outlet channel. A rotary seal is provided at a junction between the body member and barrel member.
U.S. Pat. No. 4,288,463 to Groff et al discloses a method of making pretzels of a selected spiral pitch. Dough is extruded and the extrusion is rotated about an eccentric axis into a spiral configuration for baking. The extruded dough is gravitational passed to a conveyor belt. The vertical distance that the dough downwardly passes through is varied to change the wound spiral to a selected pitch.
U.S. Pat. No. 4,445,838 to Groff discloses an extrusion apparatus for practicing the method of U.S. Pat. No. 4,288,463 to Groff et al. The extrusion apparatus includes a pressure chamber having an outlet, a hollow extrusion die journaled in the outlet, and a hollow seal which is forced fit in the outlet. The hollow seal has a neck extending slidably into the hollow die. The neck and die combine to form a rotary seal for the comestible.
Traditional breadstick manufacture involves sheeting a dough, cutting the sheet into dough preforms, placing the dough preforms into pans, fermenting or proofing of the dough, and baking the fermented or proofed dough. During fermentation or proofing, gases are produced and flavor is developed. The gas production provides cell structure and porosity in the final baked product. Increasing gas production and leavening of the dough tends to result in a highly porous, large cell structure and oven rise which is characteristic of bread.
To produce a twisted breadstick or other fermented baked goods continuously, the use of heat to reduce dough viscosity for extrudability and twistability may destroy or kill the yeast prematurely. Loss of leavening or gas production and loss of flavor development may result from the premature destruction of the yeast. In addition, pressure buildup during extrusion and twisting may cause excessive frictional heating of the dough which may also destroy the yeast. Premature leavening may also result from excessive heating of chemically leavened, non-fermented doughs.
Degasification of the dough also results from excessive die pressures. Pressure variation and extruder surging may result in loss of shape definition in the extrudate. Reducing flow rates to reduce die pressures lowers production rates and increases dough lay time. Long lay times prior to extrusion and twisting, increase gas production and bubble size in the dough which can lead to substantial degasification of the dough during extrusion and twisting. Excessive degasification of the dough during extrusion and twisting results in an undesirable glassy, dense, hard texture rather than a crispy texture in the baked product.
The present invention provides a process and apparatus for making twisted breadsticks having a tender, crisp texture with excellent shape definition on a continuous production basis. The relatively viscous dough is supplied to the twisting nozzles at a substantially constant, low pressure. The process and apparatus avoids substantial dough surging and substantial dough degasification prior to and during extrusion and twisting which would result in undesirable variations in dough rope diameter and a hard, dense, glassy baked texture in the final product.
A twisted baked good is continuously produced by forming a dough, feeding the dough to a plurality of nozzles, and extruding the dough through the nozzles and twisting the dough into a plurality of continuous twisted dough ropes without substantially increasing the density of the dough. The twisted dough ropes may be cut into pieces and then baked. The dough may be a breadstick dough or other fermented dough, the density of which decreases with increasing lay time, or which increases with an increase in pressure. The dough may be fed to the nozzles by an extruder which supplies the dough at a substantially constant pressure without substantial surging of the dough. In preferred embodiments, the dough is fed to the plurality of nozzles by a pump which supplies the dough to the nozzles at a substantially constant pressure without substantial surging of the dough. The use of low, constant pressures, avoids substantial degasification of the dough which may be caused by a build-up of pressure at the extrusion and twisting nozzles. Also, the use of low pressures avoids heat build-up at the dies which would destroy yeast present in the fermenting dough. However, the pressure is sufficiently high so as to enable consistent, smooth lamellar, plug flow, non-turbulent extrusion and twisting of the dough through multiple nozzles and orifices into smooth surface dough ropes. In embodiments of the invention, the dough is fed to the nozzles at a pressure of less than about 200 psig, for example from about 85 psig to about 140 psig and at temperatures of less than about 110xc2x0 F. Each nozzle may produce a single dough rope which is twisted about an axis. In preferred embodiments, each nozzle produces a plurality of dough ropes which are twisted together to form a continuous twisted dough rope.
The dough twisting apparatus or twist head device of the present invention includes a compression head or stuffbox for receiving a dough continuously from a pump or extruder. The compression head or housing flares outwardly and is mounted to a manifold plate by means of a flange mount. The manifold plate, upon which the compression head is mounted, contains a plurality of passages for receiving the dough from the compression head. The dough passageways are covered by the compression head or housing. The dough passageways are the widest at their upstream end at the upstream or receiving surface of the manifold plate so as to minimize dead areas on the manifold plate surface. The passageway may contain two internal chamfers, bevels or flares leading to a narrow, cylindrical passageway at the downstream or output end of the manifold plate. Each of the narrow, cylindrical passageways may contain a flow restrictor or adjustable bolt or valve for controlling or adjusting the flow through each passageway and each nozzle.
Into each outlet end or downstream end of the cylindrical passageway there is inserted an extruder pipe or stationary, hollow cylindrical shaft. The upstream end of the shaft is press fit and gas tungsten arc welded into the cylindrical passageway of the manifold plate so as to prevent leakage of the dough from the manifold plate and to assure passage of the dough through the interior hollow portion of the extruder pipe. A rotatable sleeved gear and plastic sleeve or bearing are inserted on the extruder pipe at its upstream end outside of the manifold plate. A plastic bushing may be inserted on the extruder pipe between the manifold plate and the rotatable gear to reduce frictional forces between the rotating gear and the manifold plate. The downstream portion of the gear may include screw threads for receiving a rotatable cup which is caused to rotate by rotation of the gear. A retaining ring which fits within a retaining ring groove on the extruder pipe prevents substantial movement or traveling of the rotary gear along the extruder pipe. A second bushing may be inserted on the extruder pipe downstream of the rotary drive gear to reduce frictional forces between the rotating gear and the retaining ring and to also prevent traveling of the rotary gear along the extruder pipe.
The rotatable cup includes internal screw threads for engagement with the external screw threads of the rotatable gear. The length of the rotatable cup is sufficiently long so that when the cup is securely screwed on to the rotatable gear, the downstream end of the cup extends a substantial distance beyond the end of the stationary extruder pipe so as to provide a head space within the die cup. The dough passes through the extruder pipe and out of its downstream end into the head space. The dough flows from the head space through a die hole located at the downstream end of the cup. The die hole may be provided in the end of the cup or may be present in a die insert which is held in the downstream end of the cup. One or more rubber or plastic ring seals may be provided within one or more grooves on the outer surface of the extruder pipe. The rubber ring seal helps to prevent back flow of dough between the outer surface of the extruder pipe and the inner surface of the rotatable cup back towards the gear.
Rotation of the die cup around the stationary extruder pipe, results in rotation of the die insert and die opening about the longitudinal axis of the die cup and die insert. Rotation of the die opening as the dough is extruded therethrough results in rotation of the dough as it passes through and as it passes out of the die hole.
A plurality of the rotatable gears are driven continuously and in synchronization by means of a geared belt. The geared belt is driven by a motor. The motor may be mounted on an adjustable slide plate which can be adjusted or moved to increase or decrease belt tension. The rotatable nozzles may be arranged in one or more rows. The rotatable nozzles may be arranged in two rows interstitially and driven by the same geared belt. Rotatable tensioners may be mounted or screwed into upper and lower plates of the twisting head. Each tensioner includes a rotatable sleeve gear mounted upon a non-rotatable shaft. A plastic sleeve or bearing may be employed to provide a smooth, low friction surface between the interior of the gear and the exterior of the stationary shaft. The tensioners may be located at interstitial positions above the upper row of rotatable nozzles and the lower row of rotatable nozzles. The geared drive belt may pass between the rotatable gears of the nozzles and the rotatable gears of the tensioners. The arrangement avoids contact of dough and build up of dough on the gears and avoids pulsation, surging, and the production of uneven diameter ropes.
The die insert or cup end may include one or more die holes or slots for producing a variety of twisted dough ropes. The die openings may be circular, rectangular, square, oval, straight, Z-shaped, or the like. In preferred embodiments, each die insert or cup includes three circular openings, the middle of which has its center at the longitudinal axis or rotational axis of the nozzle or cup. The remaining two circular die openings may be arranged so that the centers of the openings fall on a straight line. Upon rotation of the cup and die openings, three separate ropes are formed which form a single dough rope having a distinct, twisted appearance. The two outermost ropes twist around the inner or central rope and generally expand to a greater extent that the inner rope. The twisted dough rope contains distinctively visible peaks and valleys which are also present in the final baked product. The peaks and valleys provide an attractive variation in browning, with the peaks browning more than the valleys thereby providing a three-dimensional appearance. Three distinct ropes are visible on the outer surface of the baked product but the ropes are adhered together so that upon breaking of the pieces or eating of the pieces, the ropes do not separate or delaminate.